Grading systems in the cytological diagnosis of breast cancer: a review

In developing countries, diagnosis of breast carcinoma is still made on fine-needle aspiration cytology (FNAC). For the resource-poor settings, FNAC is cheaper, less invasive and can sample different areas of the lesion compared with core needle biopsy. The role of breast FNA is usually limited to just categorize the lesion as benign or malignant. Prognostic information from cytomorphology, conveyed to the clinician depends upon the cytopathologist's way of formatting the report. PubMed-based literature search collated the information from articles describing the architectural and cytological features studied on breast aspiration smears. This review focuses on cytomorphological features and the different grading systems with their strengths, short-comings, and practical applicability. Eight worldwide articles proposing new methods of grading the cytological smears from breast cancers were published between 1980 and 2006. All the grading methods were developed for the most common type of breast cancer, that is, infiltrating duct carcinoma (not otherwise specified) type, and most of the workers used Papanicolaou-stained smears for the purpose of grading. Moreover, if interpreted carefully FNAC smears can convey information on most of the histological features. Hence, in developing countries, the focus should be on extracting the maximum information from cytological smears, so that a more precise "surgical pathology" type diagnosis can be given, instead of merely reporting as benign or malignant. Among all the discussed grading systems, we suggest grading system by Howell would be most appropriate and closest to the accepted histologic grading system as it applies Scarff-Bloom-Richardson histological grading system with modifications on FNA smears. We recommend it to be followed by all cytopathologists, in order to bring uniformity in the reporting of breast FNAs for grading the malignant lesions.